Merge pull request #261 from Mukulbaid63/main

Floyd's Algorithm

Author: yashaswibiyahut

Java/FloydAlgorithm/FloydAlgo.java

@@ -0,0 +1,89 @@
+import java.util.*;
+import java.io.*;
+import java.lang.*;
+//Node of Linked list
+class Node
+{   
+    int data;   //value of the node
+    Node next;  //next node
+    /*Constructor*/
+    Node(int x)
+    {
+        data = x;
+        next = null;
+    }
+}
+public class DetectLoop
+{   //function to create loop in linked list 
+    public static void createLoop(Node head, Node tail, int k){
+        //base case
+        if (x == 0) return;
+        Node curr = head;
+
+        for(int i=1; i<k; i++)
+            curr = curr.next;// traversing the linked list till k
+        tail.next = curr;
+    }
+    // Driver Code 
+    public static void main (String[] args){
+        
+        Scanner sc = new Scanner(System.in);
+        
+        //no. of nodes in linked list
+        int n = sc.nextInt();
+         
+        //head of Linked list
+        int num = sc.nextInt();
+        Node head=new Node(num);
+        
+        Node tail=head;
+
+        //Linked List created
+        for(int i=0; i<n-1; i++)
+        {
+            num = sc.nextInt();
+            tail.next = new Node(num);
+            tail = tail.next;
+        }
+
+        //Node to check if loop exists or not
+        int temp = sc.nextInt();
+        
+        //creating the loop
+        createLoop(head,tail,temp);
+        
+        //creating object of x
+        Solution x = new Solution();
+        
+        //if loop exists
+        if(x.detectLoop(head))
+            System.out.println("Loop exists");
+        else
+            System.out.println("Loop doesn't exists");
+    }
+}
+
+//detecting if the loop exists or not
+class Solution {
+    
+    public static boolean detectLoop(Node head){
+        //base case
+        if(head==null||head.next==null)
+            return false;
+
+        Node slow = head;
+        Node fast = head;
+
+        while(fast != null && fast.next != null) {
+            
+            slow = slow.next;
+            fast = fast.next.next;
+            
+            //if loop exists slow and fast pointer will surely intersect
+            if(slow==fast)
+                return true;
+        }
+         
+        return false;
+    }
+}

Java/FloydAlgorithm/README.md

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+
+# Sample Input:
+
+5
+
+1 6 3 7 8
+
+2
+
+  
+
+# Sample Output:
+
+Loop exists
+
+  
+
+# Explaination:
+
+4--> size of linked list
+
+1-->6-->3-->7-->8 =>nodes of linked list
+
+2---> node to be checked
+
+</br>
+
+after creating the loop the detect loop fuction is called and the two pointer slow and fast meets if loop exists .
+For better understanding,refer <a href="https://media.geeksforgeeks.org/wp-content/cdn-uploads/20190621160855/Detect-loop-in-a-linked-list.png">here:
+  
+
+# Time complexity:
+
+O(n)